Summary of Work: Oxidative damage has been implicated in the pathology of several diseases, but only recently has it been suggested to have a role in adverse reproductive conditions. Many environmental and occupational exposures are known pro-oxidants (e.g., many solvents and metals), and they may adversely affect reproduction by causing oxidative damage. This research project explores the relationship between environmental exposures, oxidative stress, and adverse reproductive conditions. We working with two major aims. First is analysis of data from a pilot study that will resolve the amount of variability in the markers of anti-oxidant and oxidant status due to seasonal and intra-individual variation and to storage procedures, and to compare the results in pregnant and non-pregnant women. Findings to date indicate that samples cannot be stored at all for more than a few hours without altering the level of glutathione and lipid peroxides significantly. This year we finished a paper indicating high day-to-day reliability in lipid peroxides and higher values of this marker in pregnant women. There was no strong evidence of seasonal variability in our sample. A second aim is to work with laboratory scientists in designing a study to evaluate mamkers of oxidative status for suitability in epidemiologic studies. This work is a continuation of an international meeting held last fall at NIEHS that surveyed the field of oxidative stress markers. In addition, the analysis of small samples of existing data from Bulgaria concerning industrial pollutants, markers of oxidative damage, and reproductive outcome in pregnant women and their infants continues.